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August 21, 2014

Bipedal Diplodocus USNM 10865 - modified from Gilmore 1932 pl 6 - v2

I have often argued that given their long hindlimbs, massive tail-bases, and posteriorly-located centers of mass, diplodocids were basically bipeds whose forelimbs happened to reach the ground. I decided to see what that might look like.

Okay, now obviously I know that there are no trackways showing sauropods actually getting around like this. It’s just a thought experiment. But given how close the center of mass of Diplodocus is to the acetabulum, I’ll bet that this pose was achievable in life. If diplodocids had just pushed the CM a few cm farther back, they might have dispensed with forelimbs entirely, or done something different with them, like re-evolved grasping hands.

Image modified from Gilmore (1932: plate 6). Here’s a horizontal-necked bipedal Diplodocus and the original pose:

Bipedal Diplodocus USNM 10865 - modified from Gilmore 1932 pl 6

Diplodocus USNM 10865 - Gilmore 1932 pl 6 - cleaned up

UPDATE the next day: I had forgotten that Niroot had already done a bipedal Apatosaurus, and a much more convincing one than mine. Go see it.

UPDATE the next week: Well, heck. Looks like the primary value of this post was so that people would remind me of all the other places the same idea has already been covered better. As you can see from the comment thread, Mike blogged about this at the WWD site, Scott Hartman drew it, and Heinrich Mallison showed that it was plausible. Sheesh, I suck.

Reference

  • Gilmore, C. W. 1932. On a newly mounted skeleton of Diplodocus in the United States National Museum. Proceedings of the United States National Museum 81, 1-21.

Supersaurus vs Brachiosaurus - BYU 9024 and FMNH P25107

This was inspired by an email Mike sent a couple of days ago:

Remind yourself of the awesomeness of Giraffatitan:
http://svpow.files.wordpress.com/2008/11/mike-by-jango-elbow.jpeg

Now think of this. Its neck is 8.5m long. Knock of one measly meter — for example, by removing one vertebra from the middle of the neck — and you have 7.5 m.

Supersaurus’s neck was probably TWICE that long.

Holy poo.

I replied that I was indeed freaked out, and that it had given me an idea for a post, which you are now reading. I didn’t have a Giraffatitan that was sufficiently distortion-free, so I used my old trusty Brachiosaurus. The vertebra you see there next to Mike and next to the neck of Brachiosaurus is BYU 9024, the longest vertebra that has ever been found from anything, ever.

Regarding the neck length of Supersaurus, and how BYU 9024 came to be referred to Supersaurus, here’s the relevant chunk of my dissertation (Wedel 2007: pp. 208-209):

Supersaurus is without question the longest-necked animal with preserved cervical material. Jim Jensen recovered a single cervical vertebra of Supersaurus from Dry Mesa Quarry in western Colorado. The vertebra, BYU 9024, was originally referred to “Ultrasauros”. Later, both the cervical and the holotype dorsal of “Ultrasauros” were shown to belong to a diplodocid, and they were separately referred to Supersaurus by Jensen (1987) and Curtice et al. (1996), respectively.

BYU 9024 has a centrum length of 1378 mm, and a functional length of 1203 mm (Figure 4-3). At 1400 mm, the longest vertebra of Sauroposeidon is marginally longer in total length [see this post for a visual comparison]. However, that length includes the prezygapophyses, which overhang the condyle, and which are missing from BYU 9024. The centrum length of the largest Sauroposeidon vertebra is about 1250 mm, and the functional length is 1190 mm. BYU 9024 therefore has the largest centrum length and functional length of any vertebra that has ever been discovered for any animal. Furthermore, the Supersaurus vertebra is much larger than the Sauroposeidon vertebrae in diameter, and it is a much more massive element overall.

Neck length estimates for Supersaurus vary depending on the taxon chosen for comparison and the serial position assumed for BYU 9024. The vertebra shares many similarities with Barosaurus that are not found in other diplodocines, including a proportionally long centrum, dual posterior centrodiapophyseal laminae, a low neural spine, and ventrolateral flanges that connect to the parapophyses (and thus might be considered posterior centroparapophyseal laminae, similar to those of Sauroposeidon). The neural spine of BYU 9024 is very low and only very slightly bifurcated at its apex. In these characters, it is most similar to C9 of Barosaurus. However, theproportions of the centrum of BYU 9024 are more similar to those of C14 of Barosaurus, which is the longest vertebra of the neck in AMNH 6341. BYU 9024 is 1.6 times as long as C14 of AMNH 6341 and 1.9 times as long as C9. If it was built like that of Barosaurus, the neck of Supersaurus was at least 13.7 meters (44.8 feet) long, and may have been as long as 16.2 meters (53.2 feet).

Based on new material from Wyoming, Lovelace et al. (2005 [published as Lovelace et al. 2008]) noted potential synapomorphies shared by Supersaurus and Apatosaurus. BYU 9024 does not closely resemble any of the cervical vertebrae of Apatosaurus. Instead of trying to assign its serial position based on morphology, I conservatively assume that it is the longest vertebra in the series if it is from an Apatosaurus-like neck. At 2.7 times longer than C11 of CM 3018, BYU 9024 implies an Apatosaurus-like neck about 13.3 meters
(43.6 feet) long.

Supersaurus vs Diplodocus BYU 9024 and USNM 10865 - Gilmore 1932 pl 6

Bonus comparo: BYU 9024 vs USNM 10865, the mounted Diplodocus longus at the Smithsonian, modified from Gilmore 1932 (plate 6). For this I scaled BYU 9024 against the 1.6-meter femur of this specimen.

If you’d like to gaze upon BYU 9024 without distraction, or put it into a composite of your own, here you go:

Supersaurus cervical BYU 9024

References

 

Check out this beautiful Lego Diplodocus:

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(Click through for the full image at full size.)

I particularly like the little touch of having of bunch of Lego Victorian gentleman scientists clustered around it, though they’re probably a bit too big for the skeleton.

This is the work of MolochBaal, and all rights are reserved. You can see five more views of this model in his Flickr gallery. I especially admire how he’s managed to get the vertebral transitions pretty smooth, the careful use of separate radius/ulna and tibia/fibula, and the use of a transparent brick in the skull to represent the antorbital fenestra.

The forefeet are wrong — their toes should not be splayed out — but you can’t blame MolochBaal for that, as he was copying the mounted CM 84/94 cast in the Madrid museum.

 

OLYMPUS DIGITAL CAMERA

Now considered a junior synonym of Supersaurus, on very solid grounds.

Incidentally, unlike the neural spines of most non-titanosaurian sauropods, the neural spine of this vertebra is not simply a set of intersecting plates of bone. It is hollow and has a central chamber, presumably pneumatic. Evidence:

OLYMPUS DIGITAL CAMERA

Actually we had the Jurassic talks today, but I can’t show you any of the slides*, so instead you’re getting some brief, sauropod-centric highlighs from the museum.

* I had originally written that the technical content of the talks is embargoed, but that’s not true–as ReBecca Hunt-Foster pointed out in a comment, the conference guidebook with all of the abstracts is freely available online here.

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Like this Camarasaurus that greets visitors at the entrance.

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And this Apatosaurus ilium with bite marks on the distal end, indicating that a big Morrison theropod literally ate the butt of this dead apatosaur. Gnaw, dude, just gnaw.

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And the shrine to Elmer S. Riggs.

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One of Elmer’s field assistants apparently napping next to the humerus of the Brachiosaurus alithorax holotype. This may be the earliest photographic evidence of someone “pulling a Jensen“.

Cary and Matt with Brachiosaurus forelimb

Here’s the reconstructed forelimb of B. altithorax, with Cary Woodruff and me for scale. The humerus and coracoid (and maybe the sternal?) are cast from the B.a. holotype, the rest of the bits are either sculpted or filled in from Giraffatitan. The scap is very obviously Giraffatitan.

Matt with MWC Apatosaurus femur

Cary took this photo of me playing with a fiberglass 100% original bone Apatosaurus femur upstairs in the museum office, and he totally passed up the opportunity to push me down the stairs afterward. I kid, I kid–actually Cary and I get along just fine. It’s no secret that we disagree about some things, but we do so respectfully. Each of us expects to be vindicated by better data in the future, but there’s no reason we can’t hang out and jaw about sauropods in the meantime.

Finally, in the museum gift shop (which is quite lovely), I found this:

Dammit Nova

You had one job, Nova. ONE JOB!

So, this is a grossly inadequate post that barely scratches the surface of the flarkjillion or so cool exhibits at the museum. I only got about halfway through the sauropods, fer cryin’ out loud. If you ever get a chance to come, do it–you won’t be disappointed.

I need to be sleeping, not blogging, so here are just the highlights, with no touch-ups and minimal commentary.

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I don’t know what these real street signs were doing sitting on the ground when I walked to the museum this morning, but it was a good omen for the conference.

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Home base for this part of the conference. We head to Green River, Utah, on Friday for the Early Cretaceous half.

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I had never seen this on exhibit. This is not the Brachiosaurus scapulocoracoid formerly referred to “Ultrasauros”, this is the other big scap from Dry Mesa, from the giant diplodocid Supersaurus.

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Seems legit.

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This is not Dinosaur Baptist Church–it is a cathedral of an entirely different order.

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And that order is Sauropoda.

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The sauropod bones are entombed in a matrix consisting of super-hard sandstone and non-sauropod bits.

I got about 150 photos of the Wall, but only because I ran out of time. You probably already know what I’m going to attempt with them. (If not, here’s a hint.)

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Jim Kirkland (center left) literally walked us through the Morrison and Cedar Mountain Formations at this set of exposures north of the visitor center. The reddish stuff on the lower left is Morrison, and after that it’s CMF all the way up this ridge and next two behind it.

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A cast of Diplodocus carnegii at the Utah Field House of Natural History State Park Museum, signalling that we’ve come to end of this tail–er, tale.

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Further updates as time and opportunity allow. If you tweet about the conference, please use #MMFC14!

How can it be?

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All credit to the Yale Peabody Museum for having the courage to display this historically important object in their public gallery instead of hiding it in a basement. It’s the skull from the original mount of the Brontosaurus (= Apatosaurus) excelsus holotype YPM 1980.

Needless to say, it bears no resemblance at all to the actual skull of Apatosaurus, and the one they now have on the mount is much, much better:

IMG_0500-skull

But how did the YPM people ever arrive at this double-plus-ugly skull above? We see a similar skull in Marsh’s (1891) second attempt at restoring the skeleton of Brontosaurus:

Marsh1891-plateXVI-Apatosaurus-skull

But even this is not as ugly and Just Plain Wrong as the physical model they made. (Marsh’s first restoration of the Brontosaurus skeleton, in 1893, had a much less clear skull.)

So how did the YPM come to make such a monstrosity? What was it based on? Tune in next time for the surprising details!

Bizarrely, we’ve never really featured the  YPM 1980 mount here on SV-POW! — we’ve often shown individual bones, but the mounted skeleton appears only in the background of the much less impressive Morosaurus (= Camarasaurus) lentus mount. We’ll fix that real soon.

 

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